Conventionally, inspecting and managing air pressure of tires mounted on vehicles has been desirable from the perspectives of enhancing tire durability, wear resistance, fuel economy, riding comfort, and driving performance. Therefore, various systems for monitoring air pressure of tires have been proposed. Generally, in these systems, air pressure in tires is monitored by acquiring the air pressure information of a tire assembled on a vehicle wheel as tire information, providing a tire information acquisition device for transmitting this tire information in the tire cavity region, and acquiring the tire information of each of a plurality of tires mounted on a vehicle from the tire information acquisition device.
As a specific explanation of a vehicle wheel provided with a tire information acquisition device, for example a tire information acquisition device S is provided on a surface side of a rim R facing the tire cavity region, as shown in FIG. 13A, and a tire valve V is installed penetrating an inclined face of a rim hump R1 with a protruding form formed on the rim R. Also, a tire T is fitted to the surface of the rim R facing the tire cavity region. In such a vehicle wheel, when the tire T is removed from the rim R, the tire T moves along the surface of the rim R in the wheel width direction (the direction of the arrow in FIG. 13A). Here, as shown in FIG. 13B, if after riding over the rim hump R1, the tire T drops into a depression formed at the connection between the tire information acquisition device S and the tire valve V, the tire information acquisition device S is an obstruction on the path of movement of the tire T, in particular the tip portion of the bead portion of the tire T, so the tire information acquisition device obstructs the movement of the tire T. In this case, there was the problem that the tire information acquisition device S is separated from the tire valve V by the excessive force or shock of the impact with the tire T, or is damaged.
For this problem, a tire air pressure sensor fitting structure and tire wheel have been proposed in which the sensor can be removed or damage can be avoided when removing the tire from the rim (Japanese Unexamined Patent Application Publication No. 2007-191069A).
Specifically, a pair of protective members is provided on the rim of the tire wheel to protect the sensor from contact interference with the tire inner peripheral edge when fitting or removing the tire. The pair of protective members is provided sandwiching the sensor in the rim circumferential direction, to prevent contact between the tire and the sensor when fitting or removing the tire.
In the tire air pressure sensor fitting structure and tire wheel disclosed in Japanese Unexamined Patent Application Publication No. 2007-191069A, the protective member is provided integral with the rim, so if for example a tire air pressure monitoring system is constructed using a plurality of tire air pressure sensors each of different size, the positions of the protective members on the rim surface will differ depending on the air pressure sensor. Therefore, it is necessary to carry out a process to change the form of the rim in accordance with the size of the air pressure sensor, in other words it is necessary to separately manufacture the tire wheels, so the versatility of the tire wheel suffers, and the manufacturing cost of the tire wheel could increase.